February 1, 2011 – Eulitha AG and Dai Nippon Printing (DNP) say they have successfully patterned 4-in Si wafers with Eulitha’s "PHABLE" technology, creating uniform photonic crystal patterns with 600nm period and hexagonal symmetry.
The PHABLE ("Photonic Enabler") is a mask-based UV lithography technology that enables formation of periodic nanostructures over large areas, forming an image with a very large depth-of-focus (the company has called it "practically unlimited") to accommodate patterning on even nonflat substrate surfaces. Combinations of different patterns (e.g. hexagonal or square grids) can be printed using a single exposure, with feature resolution as small as a 1/4 of the illumination wavelength.
Achieving uniform patterning on 4-in. wafers (using a DNP high-resolution mask on standard quartz/Cr plate) is an important milestone, the companies say. HB-LED makers are moving up to the next bigger wafer sizes (4-in. and 6-in.). Photonic crystal structures that enhance LED light extraction, or patterned sapphire substrates, can be fabricated with the PHABLE technology — as can required substrates for nanowire-based LED or solar-cell applications.